1. Field
One embodiment of the invention relates to a storage device using a nonvolatile cache memory which is designed to realize low power consumption and high-speed read/write operation and attain a long service life of a storage medium and a control method thereof.
2. Description of the Related Art
In recent years, a storage device on which both of a memory card which is a semiconductor storage medium and a hard disk (HD) drive using a hard disk which is a magnetic storage medium can be mounted is developed (refer to Jpn. Pat. Appln. KOKAI Publication No. 2004-055102). For example, data of the memory card fetched from the exterior can be backed up into the hard disk (HD) which is a magnetic storage medium. Further, data of a hard disk (HD) can be transferred to the memory card and can be thus taken out.
As a mobile storage device, a storage device using a flash memory is developed (refer to Japanese Patent Publication No. 3407317). A large number of errors occur in the flash memory when the number of erase operations of the flash memory becomes large (for example, 100,000 times), and therefore, an attempt is made to solve the above problem. For example, a data management method for suppressing the number of erase operations for a specified area from becoming larger is provided.